This invention relates generally to data display and control systems and more particularly to a technique for the dynamic control of horizontal scrolling on a data display device.
In data processing systems, an application often has information for users that is too large to fit on the display screen. Applications, therefore, provide users with the ability to scroll information both vertically and horizontally. Furthermore, in a windowing environment, scrolling capabilities are even more important because several windows can appear on the screen simultaneously, limiting the space available for information in each window. Users have the ability to change the size of windows dynamically in a windowing environment, further limiting the available display space.
During the horizontal scrolling of a display list containing more columns of information than can be displayed simultaneously, certain columns are made "sticky" in order to provide the view-to-view continuity necessary to maintain the context of the data. Sticky columns are those columns in a displayed list that remain in place when the user makes a request to scroll the list horizontally. Sticky columns usually represent key values that help to identify a row and remain in place when the remainder of the columns are shifted. Sticky columns are always the leftmost columns in a displayed list and can fill the entire display window.
Several existing systems use combinations of hardware and software to control the scrolling of data on display screens. One example is U.S. Pat. No. 4,803,478 to Olsen. This patent teaches an apparatus for horizontal scrolling on a screen display on a character-by-character, or line-by-line basis. A scroll control memory is provided with the video memory for storing at least one bit for controlling horizontal scrolling on a character-by-character basis.
Other related art includes U.S. Pat. No. 4,769,637, U.S. Pat. No. 4,602,251, U.S. Pat. No. 4,412,294, U.S. Pat. No. 4,873,514 and U.S. Pat. No. 4,506,343. However, none of the aforementioned patents provide a capability for the software-controlled horizontal scrolling of a stored list of data of arbitrary size in a window on a display screen that can be dynamically altered through the user's interface with an application. Existing software applications permit horizontal scrolling of data through a stored list; however, these applications are tailored specifically for the data in the stored list. Consequently, the stored list has a fixed and known table dimension, and the data is displayed on the entire screen. A specific example is the CALLUP software product, a licensed program of International Business Machines Corporation. CALLUP is an internal telephone book, organization directory, and directory of services in electronic form.
The present invention overcomes this deficiency of existing systems.